Herb Fennel

Apiaceae

Tall herb (3-6 feet) with feathery foliage, flat-topped yellow flowers, and anise-flavored fronds and seeds. Perennial zones 7-10, biennial 5-6, annual zone 4. CRITICAL: ALLELOPATHIC — root exudates (anethole, fenchone) inhibit growth of 80%+ of common garden plants. MUST be isolated 4-6+ feet from vegetable garden. Long taproot — direct sow, does not transplant well. Host plant for black swallowtail butterfly. Can cross-pollinate with dill.

At a Glance

Days to Maturity

60–70 days

Sun

6+ hours

6+ hours full sun

Spacing

12–18 "

Container

Yes

5+ gallon pot

Height

3–6 ft

Zone Planting Guide

Your USDA Zone:

Growing Guide

Germination

Germination Time 7–10 days

Optimal Temp 65°F

Watering

Weekly Water 1–1.5 "

Needs Moderate

Soil

pH Range 5.5–7

Soil Type Rich, well-drained, loamy

Resilience

Heat: Moderate-high Cold: Moderate Drought: Medium

Nutrition

Feeding Intensity Moderate feeder

Companion Planting

Avoid Planting Near

Roma vf tomato 30% yield reduction within 6 feet.

California wonder pepper Allelopathic damage.

Blue lake bush bean Disrupts N-fixing bacteria.

Dill Cross-pollination produces off-flavored seeds.

Nantes carrot 37% yield loss at close spacing.

Sources

university Wisconsin Horticulture — Fennel university Illinois Extension — Fennel university Utah State Extension — Fennel

More Herbs

Herb Fennel Planting Dates by Zone

Planting dates for Herb Fennel vary by USDA hardiness zone. Select your zone below for frost dates, start-indoors timing, and a full monthly planting calendar.

Zone 5A Zone 5B Zone 6A Zone 6B Zone 7A Zone 7B Zone 8A Zone 8B Zone 9A Zone 9B

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